Other than sanding it down and repainting there is not much that can be done. Have a look at my galley build, in my signature, that paint job is all done by brush. Some of that is up to twelve coats, I use the cheapest of acrylic paints, the kind in the plastic bottles that cost under $2.00. The secret is to thin your paints, I do about 50/50, and apply several coats. The paint drys fast enough you can easily apply several coats per day.
I always apply a primer of some sort, meaning a actual primer paint or something as simple as wipe on poly. Sand this smooth with a fine sandpaper then start painting. I do not sand in between every coat but rather every five or six coats depending on coverage. When I can see that that the coverage is almost done I refrain from sanding between the last two coats. Try not to over brush.
It is a good idea not to leave your masking tape for days after painting but take it off as soon as possible. When removing the tape pull it away from the painted area not towards it, this will help with peeling the paint off.
These are just some of my techniques, and I hope they help. Other than using a spray can for priming I never spray, old school
, and I am very happy with the results I get.
Have a good one